Medicine and alcohol – which combinations are risky
Which common medicines should not be mixed with alcohol, why some combinations are dangerous rather than merely unwise, and what to do at a social occasion.
Three different kinds of problem
- Alcohol adds to the effect. Sedatives, sleeping tablets, strong painkillers, some antihistamines and some mental-health medicines all cause drowsiness, and alcohol multiplies it. At the extreme this slows breathing.
- Alcohol changes how the medicine is handled. It can raise or lower the level of a medicine in the blood, which matters most where the safe range is narrow — blood thinners and epilepsy medicines among them.
- The combination is directly toxic. Alcohol and some medicines together are harder on the liver or the stomach than either alone.
Combinations worth knowing about
- Some antibiotics cause severe flushing, nausea and vomiting with even a small amount of alcohol, and the warning extends for a period after the course finishes.
- Blood thinners: alcohol affects how they work, and the consequence is either bleeding or a clot rather than a hangover.
- Sedatives, sleeping tablets and strong painkillers: the combined sedation is the mechanism behind many accidental deaths.
- Paracetamol and heavy or regular drinking: both are processed by the liver, and the combination raises the risk of liver damage, especially if doses are also being exceeded.
- Anti-inflammatory painkillers: alcohol adds to the risk of stomach bleeding.
- Diabetes medicines and insulin: alcohol can cause low blood sugar hours later, including overnight, and the symptoms are easily mistaken for being drunk.
- Medicines that already cause drowsiness or dizziness: adding alcohol makes falls and road accidents far more likely.
Medicines where alcohol is a specific issue rather than a general caution:
Metronidazole — Flagyl, Adco-Metronidazole, Metrosa, Medazol
Anaerobic infections; Trichomonas; bacterial vaginosis; Giardia; amoebic dysentery; C. diff
Warfarin — Cipla-Warfarin, Marevan, Coumadin, Warfant
Prevention and treatment of VTE; atrial fibrillation; mechanical heart valves
Paracetamol — Panado, Painamol, Tylenol, Pacimol
Mild to moderate pain; fever
Diazepam — Valium, Pax, Diapin, Antenex
Acute anxiety; alcohol withdrawal; acute seizures; muscle spasm; status epilepticus
Metformin — Glucophage, Glucophage XR, Sandoz Metformin, Adco-Metformin
Type 2 diabetes mellitus — first-line agent
Practical answers
- Ask the pharmacist when you collect anything new. Ask about your whole list, not only the new item.
- Do not skip doses in order to drink. Missing epilepsy, HIV, TB, mental-health or heart medicine to have a night out is worse than the interaction you were avoiding.
- If you are going to drink anyway, say so honestly. The advice you get will be safer than the advice given to a person pretending they do not.
- Do not drive. This applies at a much lower level of alcohol when combined with a sedating medicine.
- Eat, and alternate with water — this helps most with the low-blood-sugar risk on diabetes treatment.
Common questions
- Can I drink alcohol on antibiotics?
- It depends on the antibiotic. Some cause severe flushing and vomiting with even a small amount, with the warning extending past the end of the course; others carry no specific interaction. Ask the pharmacist about the one you were given.
- Should I skip my medicine if I want to drink?
- No. Missing doses of epilepsy, HIV, TB, mental-health or heart medicine is more dangerous than the interaction you are avoiding. Ask a pharmacist how to handle it instead.
- Is paracetamol safe with alcohol?
- Both are processed by the liver, so regular or heavy drinking with paracetamol raises the risk of liver damage — especially if the daily maximum is also exceeded. Check the total dose across every product you are taking.
Sources
- Medicines Online Directory and approved patient information leafletsSouth African Health Products Regulatory Authority
- Adult Hospital Level Standard Treatment Guidelines and Essential Medicines ListNational Department of Health, South Africa
- Poisons Information Helpline guidanceTygerberg and Red Cross Poisons Information Centres
- Clinical and public health guidanceWorld Health Organization
Last reviewed 11 August 2026.